port question

[David A. Bandel]

On Sat, Aug 22, 2009 at 22:26, Tony Alfrey<tonyalfrey at earthlink.net> wrote:
> Consider Alice, Bob and Tony.
>
> Bob and Alice are computer illiterate, Tony perhaps less so.
>
> Bob sends email to Alice's POP server.  For some reason, Alice's POP server
> does not receive this mail, or more accurately, does not process it.
> Bob sends the same email to Tony's POP server, no problem.

First, a pop server is a post office protocol server.  It uses port
110 or port 995.  SMTP uses port 25 or another port.  Unofficially,
465 is the SSL port.

You send mail to an e-mail server, not a pop server.

Unless of course you're referring to point-of-presence.  But don't
call it a server, it's just their POP.

>
> Tony says to Bob:  "What port are you using for your SMTP server?"
> Bob says "Say what?"
>
> Tony says to Alice: "Does your POP server perhaps block port 25?"
> Alice says "Say what?"
>
> How can Tony examine the incoming e-mail to know the port?  Tony does not
> host a server, so Tony cannot receive the raw packet stream, Tony can only
> read the e-mail after it has been received by Tony's POP server (more
> accurately, the POP server for Tony's domain hosting service).

Why would Tony need to examine incoming mail?  If he wants to know if
port 25 between himself and Alice is blocked, all he has to do is:

telnet "Alice's email server" 25
he can connect or not.

To find Alice's email server:
dig MX "Alice's e-mail domain"

BTW: ports don't show up in e-mail headers, only IPs.  More likely,
Alice's spam filters are plonking Tony.

>
> Thanks in advance.
>
>
> --
> Tony Alfrey
> tonyalfrey at earthlink.net
> "I'd Rather Be Sailing"
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>


David A. Bandel
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